1. Field of the Invention
The present invention relates to a multi-functional cyclic siloxane compound, a siloxane-based polymer prepared from the compound and a process for preparing a dielectric film using the polymer. More specifically, the present invention relates to a multi-functional cyclic siloxane compound (A); a siloxane-based (co)polymer prepared from the compound (A), or the compound (A) and at least one of Si monomer (B) having organic bridges, acyclic alkoxy silane monomer (C), and linear siloxane monomer (D) and a process for preparing a dielectric film using the polymer.
2. Description of the Related Art
As the degree of integration in semiconductor devices increases, R (resistance)×C (capacitance) delay also increases, resulting in serious problems such as a signaling transfer delay. So, how to reduce the capacitance of an interlayer dielectric film has been a matter of the greatest concerns in the field of semiconductor production technology, and various attempts have been made to develop low dielectric materials for use in the production of enhanced dielectric films.
For example, U.S. Pat. Nos. 3,615,272; 4,399,266; 4,756,977; and 4,999,397 disclose dielectric films produced by spin on deposition (SOD) using polysilsesquioxanes (dielectric constant: about 2.5-3.1) instead of SiO2 (dielectric constant: 4.0) that should be deposited by chemical vapor deposition (CVD). Also, hydrogensilsesquioxanes as well as methods for their preparation are well known in the art. For example, U.S. Pat. No. 3,615,272 discloses a method of preparing a completely condensed, soluble hydrogensilsesquioxane, which comprises the steps of condensing trichloro-, trimethoxy- and triacetoxy-silanes in a sulfuric acid medium and then washing the resulting resin with water or aqueous sulfuric acid. U.S. Pat. No. 5,010,159 also discloses a method of synthesizing a condensed hydrogensilsesquioxane resin, which comprises the steps of hydrolyzing hydrosilanes in an arylsulfuric acid hydrate-containing hydrolysis medium and then contacting the resulting resin with a neutralizing agent. U.S. Pat. No. 6,232,424 describes a highly soluble silicone resin composition very stable in solution, which is prepared by hydrolyzing and polycondensing tetraalkoxysilane, organosilane and organotrialkoxysilane monomers in the presence of water and an appropriate catalyst. U.S. Pat. No. 6,000,339 teaches that a silica-based compound, having improved oxygen plasma-resistance, improved physical properties and thickness of a coating film, can be obtained from the reaction of a monomer selected from the group consisting of alkoxysilane, fluorine-containing alkoxysilane and alkylalkoxysilane and a titanium- or zirconium-alkoxide compound in the presence of water and an appropriate catalyst. U.S. Pat. No. 5,853,808 discloses that siloxane- and silsesquioxane-based polymers useful for producing SiO2-rich ceramic coatings can be obtained from hydrolysis and polycondensation of organosilanes possessing a β-substituted alkyl group. On the other hand, EP 0 997 497 A1 discloses that hydrolysis and polycondensation of a certain combination of alkoxysilanes including mono-, di-, tri- and tetra-alkoxysilanes as well as trialkoxysilane dimers can provide useful insulating materials. Meanwhile, U.S. Pat. No. 5,378,790 discloses inorganic/organic hybrid materials of excellent physical properties. U.S. Pat. No. 6,660,822 discloses a siloxane-based resin composition obtained from hydrolysis and polycondensation of circular siloxane monomers and a thin dielectric film produced therefrom.
However, dielectric films produced using those prior siloxane-based resins cannot achieve a satisfactory low dielectric constant, or they are deficient in mechanical properties and contain excessive carbon even though having a low dielectric constant. In particular, polymers prepared from a Si compound of Q structure, such as tetramethoxysilane, have good mechanical properties, but their high dielectric constant, due to inherent strong hygroscopicity, inhibit their use in the production of dielectric films, more particularly in the production of dielectric films through the SOD process. Recently, siloxane-based resins are required to have a good compatibility with pore-generating materials usually used for the purpose of further lowering the insulating coefficient thereof.
Consequently, there is a necessity for developing novel insulating materials that can be applied to a SOD process to produce dielectric films having a low insulating coefficient and good mechanical properties and which are compatible with pore-generating materials.